Flexible Touchpad Electrode Structure for Bending Reliability
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Solution Overview
Problem
Flexible touch screens face challenges with cracking and shedding of ITO electrodes during bending tests, and the high reflectivity of metal electrodes causes visual shadows, affecting display quality.
Innovation Solution
A touch electrode structure with a metal layer and buffer layer for improved adhesion and ductility, combined with a low reflectivity metal oxide layer, and organic insulating layers with different refractive indices to reduce reflectivity and eliminate metal shadows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ITO is used as the sensing electrode in flexible touch screens, then the touch sensitivity is maintained, but cracking and shedding occur during bending tests
Solution Approach 1:
The patent applies composite materials by creating a multi-layer structure consisting of a buffer layer (Ti, Ti alloy, Mo, or Mo alloy) combined with a metal layer (Ag or Cu). This composite structure combines the adhesion benefits of the buffer layer with the ductility and conductivity of the metal layer, solving both the cracking issue during bending and maintaining touch sensitivity.
Solution Approach 2:
The buffer layer serves as an intermediary between the substrate and the metal layer. It mediates the stress during bending and provides strong adhesion to the substrate while allowing the metal layer to maintain its ductility and electrical properties, preventing both cracking and shedding.
2Reliability
If metal is used as the electrode wire to improve ductility, then bending performance improves, but high reflectivity causes visual shadows affecting display quality
Solution Approach 1:
The patent applies local quality by making different parts of the electrode structure have different optical properties. The buffer layer and metal layer are designed with specific thicknesses and materials to control light reflection locally, reducing the visual shadow effect while maintaining the ductility needed for bending performance.
3Stability of the object's composition
If metal layer is used to replace ITO, then ductility is improved, but adhesion force to substrate deteriorates
Solution Approach 1:
The patent uses composite materials by combining a buffer layer with strong adhesion properties (Ti, Ti alloy, Mo, or Mo alloy) with a metal layer (Ag or Cu) that provides excellent ductility. This composite structure allows the metal layer to maintain its compositional stability and ductility while the buffer layer ensures strong adhesion to the substrate.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances bending performance, touch sensitivity, and visual clarity by reducing reflectivity differences between metal and non-metal areas, ensuring stable and high-performance flexible touch screens.
Implementation Method 1
the buffer layer is made of metal or metal alloy which improves the adhesion force between the metal layer and the substrate
Implementation Method 2
above the metal layer is disposed a metal oxide layer with low reflectivity
Implementation Method 3
organic insulating layers with different refractive indices to reduce reflectivity and eliminate metal shadows
Data Source
AI summary
The disclosure provides a touchpad and a display screen thereof. The touchpad includes a first touch electrode assembly and a second touch electrode assembly; the first touch electrode assembly includes a first touch electrode and a first organic insulating layer covering the first touch electrode; and the second touch electrode assembly includes a second touch electrode and a second organic insulating layer covering the second touch electrode. The touch electrode includes a metal layer, a buffer layer and a low reflection layer, the buffer layer being disposed below the metal layer, and the low reflection layer being disposed above the metal layer.